For purposes of improving the lift on an aerodynamically effective wing, an aerofoil, a large number of high lift components are of known prior art, which serve to increase the curvature and/or the extent of the wing profile in the wing chordwise direction, and thus to increase the lift of the aerofoil. In high lift components, which with reference to the flow direction are provided on the front of the aerofoil profile, a differentiation is to be made between nose flaps, which essentially are joined to the front of the actual wing or main wing without any discontinuity, and leading edge slats, in which, at least in the extended state, a gap is present between the trailing edge of the leading edge slat and the leading edge of the main wing, through which high energy air, that is to say, air flowing at high velocity, is fed from the lower surface of the leading edge slat to the upper surface of the main wing, which results in a further increase in lift.
High lift components in the form of leading edge slats serve to provide extra lift for modern passenger and freight aircraft with a high takeoff weight. In one of the simplest, and therefore preferred, kinematic systems the leading edge slat as it extends moves on a circular track around an axis of rotation located underneath the forward region of the main wing, wherein the leading edge slat in a retracted cruise setting lies flat against the front of the main wing and supplements the profile of the latter to form a suitable shape for cruise flight. To increase the lift the leading edge slat is extended by pivoting around the said axis of rotation whilst increasing the curvature and the extent of the total wing profile in the wing chordwise direction, wherein with the circular arc kinematics cited a gap gradually forms between the trailing edge of the leading edge slat and the wing profile in the nose region of the main wing as the leading edge slat extends. While such a gap, leading high energy air from the lower surface of the leading edge slat to the upper surface of the main wing, is of advantage for the landing approach on account of its effect in increasing lift and delaying boundary layer separation and is thus desirable, it is disadvantageous for takeoff, on the other hand, on account of the increased drag that is associated with it. In general, therefore, an attempt is made to configure the actuation kinematics for the leading edge slat such that the leading edge slat in a first partially extended setting is suitable for takeoff, with its trailing edge lying flat against the main wing, and in a second, further extended setting is suitable for landing, with its trailing edge spaced apart from the surface skin of the main wing in the region of the profile nose of the latter, so as to open up a gap feeding high energy air from the lower surface of the leading edge slat to the upper surface of the main wing.
From U.S. Pat. No. 4,399,970, U.S. Pat. No. 5,839,699 and U.S. Pat. No. 6,682,023 high lift aids in the form of leading edge slats are of known art, in which the leading edge slat in the retracted position, in the takeoff position, and intermediate positions, does not open up any gap between leading edge slat and main wing. Such a gap is only continuously open during the further extension of the leading edge slat into the landing configuration. This is achieved by means of additional kinematic elements or (in the case of U.S. Pat. No. 5,839,699) by an adaptation of the nose profile of the main wing to the curved track of the leading edge slat trailing edge. Linked with such measures are, accordingly, either an increased weight as a result of the additional kinematic elements, or an aerodynamically disadvantageous gap geometry in the adaptation of the nose of the wing in the case last cited.
Furthermore from U.S. Pat. No. 4,753,402 a leading edge slat that can be extended relative to the main wing by means of arcuate rails is of known art, which is mounted such that it can rotate through a small angle relative to the rails and is pre-loaded by means of a leaf spring arrangement against the rails such that the gap between leading edge slat and main wing is increased if a certain aerodynamic force is exceeded, in that the trailing edge, directed rearwards, facing the main wing, is displaced against the spring force forwards and upwards. The leading edge slat itself has a rigid, unchanging profile.